Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Quem patrocinou a vitória de Greg Biffle em 14 de abril?
 ###Tabelas: CREATE TABLE nascar_sprint_cup_series_race_winners (nascar_sprint_cup_series_race_winners_id AUTO_INCREMENT PRIMARY KEY, Season INT, Date VARCHAR, Winning Driver VARCHAR, Car # INT, Sponsor VARCHAR, Make VARCHAR, Distance VARCHAR, Avg Speed VARCHAR, Margin of Victory VARCHAR) CREATE TABLE donald_campbell's_unlimited_world_water_speed_records (donald_campbell's_unlimited_world_water_speed_records_id AUTO_INCREMENT PRIMARY KEY, Speed VARCHAR, Craft VARCHAR, Pilot VARCHAR, Location VARCHAR, Date VARCHAR) CREATE TABLE series_4:___1999 (series_4:___1999_id AUTO_INCREMENT PRIMARY KEY, Episode No. VARCHAR, Episode Title VARCHAR, UK Broadcast Date VARCHAR, Presenter VARCHAR, Details of Journey VARCHAR, Countries Visited VARCHAR) CREATE TABLE origins_in_corporate_strategy (origins_in_corporate_strategy_id AUTO_INCREMENT PRIMARY KEY, Component VARCHAR, Integrated VARCHAR, Allied-Related VARCHAR, Allied-Unrelated VARCHAR, Holding VARCHAR) CREATE TABLE narrowest_margin_of_runs_victory (narrowest_margin_of_runs_victory_id AUTO_INCREMENT PRIMARY KEY, Score VARCHAR, Opposition VARCHAR, Venue VARCHAR, City VARCHAR, Year INT)  
SELECT Sponsor FROM nascar_sprint_cup_series_race_winners WHERE Winning Driver = greg biffle AND Date = april 14